Oralloy
From your referenced sites
The date that a third weapon could have been used against Japan was no later than August 20. The core was prepared by August 13, and Fat Man assemblies were already on Tinian Island. It would have required less than a week to ship the core and prepare a bomb for combat.
By mid 1945 the production of atomic weapons was a problem for industrial engineering rather than scientific research, although scientific work continued - primarily toward improving the bomb designs.
The three reactors (B and D which went started up for production in December 1944, and F which started up February 1945) at Hanford had a combined design thermal output of 750 megawatts and were theoretically capable of producing 19.4 kg of plutonium a month (6.5 kg/reactor), enough for over 3 Fat Man bombs.
Monthly or annual production figures are unavailable for 1945 and 1946,
but by the end of FY 1947 (30 June 1947) 493 kg of plutonium had been produced. Neglecting the startup month of each reactor, this indicates an average plutonium production 5.6 kg/reactor even though they were operated at reduced power or even shut down intermittently beginning in 1946.
A very interesting and potentially informative site. However I have two problems with it
1) The author does not reference his statements, which are presented as drawn from available documents and archives.
2) The main menu lists a bibliography but it is not available on line.
A third observation, which I have no means of evaluating:
If the "theoretical" production capabilities in 1945, beginning in February, was sufficient for three bombs a month, why was there not sufficient material on hand for 15 bombs by August 1945?
The author of the site has a point of view, "anti nuclear" which is commendable and is similar to my own. But I question the degree to which his views have colored his presentation of the material
Author of site: Carey Sublette
Home Page address
http://www.nuclearweaponarchive.org/